hai this is my first response ,so i am just giving my opinion ,as you hav told that cust is having a problem with PSIS ,just check with her regular sitting posture becuase software people are not bothered about their posture ,so she must hav strained a sciatica ,due to which she is having pain in her leg,and calf ,so the solution would be try giving mild manual traction ,make the patient lie in supine position bend (very slowly)both the knees to 90 degrees and keep 3 pillows under the knees .
you must gradually increase the height to 90 because patient will hav severe pain ,so increase the height to 70 leave in the same position for 10 min then increase the range for 10 degrees leave it for 10 min ,GRADUALLY INCREASE THE HEIGHT ,so keep repeating this position per day for 5 min then for 10 min and slowly increase the time ,but when patients comes to normal supine lyeing from crook lyeing may hav severe pain so hav to wait in the same posture for some time ,then correct the standing posture by giving mental confidence ,she may improve ,but PSYCHOLOGY PART IS VERY IMPORTANT HERE .
I hav tried it ,has given me good result , you may also try .